diff --git a/src/commands/pubsub-shardnumsub.json b/src/commands/pubsub-shardnumsub.json
index 8eeca4e31b..75f7742fc0 100644
--- a/src/commands/pubsub-shardnumsub.json
+++ b/src/commands/pubsub-shardnumsub.json
@@ -20,6 +20,25 @@
                 "multiple": true
             }
         ],
+        "key_specs": [
+            {
+                "flags": [
+                    "NOT_KEY"
+                ],
+                "begin_search": {
+                    "index": {
+                        "pos": 1
+                    }
+                },
+                "find_keys": {
+                    "range": {
+                        "lastkey": -1,
+                        "step": 1,
+                        "limit": 0
+                    }
+                }
+            }
+        ],
         "reply_schema": {
             "description": "The number of subscribers per shard channel, each even element (including 0th) is channel name, each odd element is the number of subscribers.",
             "type": "array"